Multilayer imageable articles are known in the art with various color-forming layers separated from each other by barrier interlayers. Additionally, it is common practice in the imageable arts to apply a protective barrier layer to the top surface of an imageable construction in order to prevent abrasion and environmental deterioration of the imageable construction. In both of these applications, impermeability to chemical diffusion is an important factor in determining the success of the barrier layer.
Photothermographic articles having at least two or three distinct color image-forming layers are disclosed in U.S. Pat. Nos. 4,021,240 and 4,460,681. The barrier layers are "functional" when ingredients active in the formation of color are included therein. The layers are considered "non-functional" when no ingredients active in the formation of dye images or silver images are included within that layer.
U.S. Pat. No. 4,021,240 discloses the use of interlayers of polyvinyl alcohol for preserving the integrity of multiple color-forming layers. Other hydrophilic polymers, such as gelatin, are also disclosed as being useful. The use of other synthetic polymeric binders, alone or in combination, as vehicles or binding agents in various layers is described. Useful resins such as polyvinyl butyral, cellulose acetate butyrate, polymethyl methacrylate, ethyl cellulose, polystyrene, polyvinyl chloride, chlorinated rubber, butadiene-styrene copolymers, and vinylchloride-vinyl acetate copolymers are also disclosed.